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Homework Help: Concentration Problems

  1. Feb 17, 2012 #1
    1. The problem statement, all variables and given/known data
    15 cm3 of 0.200 mol dm-3 sodium hydroxide solution was made up to 100 cm3 with 0.120 mol dm-3 sodium sulfate solution. Determine the molar concentration of sodium cations in the resultant mixture.

    2. The attempt at a solution
    Moles of sodium ions in sodium hydroxide = 0.200 x (15/1000) = 0.003 mol
    Let volume of sodium sulfate be Vx.
    (0.120Vx) x 2 + 0.003 = Total moles of sodium ions

    After which, i find it hard to proceed. :(
  2. jcsd
  3. Feb 17, 2012 #2


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    Staff: Mentor

    You started with 15 mL, now you have 100 mL. How many mL were added?
  4. Feb 17, 2012 #3
    85 mL? But I remember that particles can fit into small spaces, so surely 85 mL is wrong?
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